


Central City under attack

by ourvelvetscars



Category: Shadowhunters (TV), The Flash (TV 2014)
Genre: Demons, F/M, M/M
Language: English
Status: Completed
Published: 2018-07-28
Updated: 2018-07-28
Packaged: 2019-06-17 16:27:57
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 1,898
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/15465441
Author URL: https://archiveofourown.org/users/ourvelvetscars/pseuds/ourvelvetscars
Summary: Inspired by another one of my insane dreams, this is a crossover between Team Flash and the Shadowhunter world. When demons attack Central City and Barry is attacked, there is only one solution left.





	Central City under attack

The sirens went off echoing throughout STARLabs- those that indicated the opening of a breach.

“Barry! We have trouble!” Cisco yelled immediately checking the systems.

Barry sped in glancing around, “what’s happening? Why are there breaches opening everywhere? I thought we closed them all?”

Iris and Caitlin stormed in looking horrified as images of winged monstrous creatures entering their world appeared on the screens.

“Cisco?” Iris asked demanding answers.

“I have no idea what’s happening Iris,” Cisco said tapping the control panel.

“But there isn’t a breach under STARLabs?” Caitlin asked confused.

“Apparently not. I don’t understand that either,” Cisco stammered.

“Wait here, I’ll check it out,” Barry said speeding away.

“BE CAREFUL BARRY! WE DON'T KNOW WHAT WE'RE FACING!” Cisco yelled behind him.

\-----

Barry arrived at their closest breach opening in Central City only to be left completely speechless and feet frozen into the ground.

“Uhh guys are you seeing this??” Barry communicated. There were winged creatures flying out of the light blue breaches shrieking as they sped out.

“What in the world?” Cisco muttered bamboozled back at STARLabs.

Meanwhile Barry raced around creating his infamous lightning bolt and aimed it at one of the winged creatures that just left the breach. Barry’s aim was spot on as always but the lightning had little to no effect on the creature. It screeched, faltered a little as it continued to fly on. Barry completely stunned didn’t see the massive creature that came up from behind him and scratched its claws into Barry’s back. The Flash yelled as the pain coursed through his blood.

“BARRY!” 3 voices yelled from the intercom. A new breach opened, Cisco jumped out and grabbed his injured friend and hobbled back into the light blue light. The two arrived at STARLabs with Barry who was having trouble breathing.

“Take his suit off!” Caitlin demanded. Iris and Cisco helped him out of his suit, to reveal a wound deep into the bone. They placed him on the bed and the moment Barry’s head hit the pillow, he blacked out.

\-----

Barry woke up to an unfamiliar voice. Tired and drained, he forced his eyes to open. There was no one in the room but he could hear raised voices coming from the main room.

“We don’t even know who you are and you want us to just blindly trust you?” Iris enquired.

“I understand that, I do. But there are demons from my world that is currently destroying YOUR world as we stand here and argue. Believe it or not, I know how to destroy those demons and right now, it looks like you could use my help,” a deep stern voice replied. Barry stood up slightly wavering and opened the door.

“Barry, you shouldn’t be up…” Caitlin said as she immediately came to Barry’s aid.

“Who is he?” Barry asked examining the man standing before him. He was dressed in all black clothing with weaponry hanging from his belt. The man really looked like he had been to hell and back.

“I’m Alec. In my world I’m known as a Shadowhunter. We kill demons like the ones ruining your world,” Alec said strictly but with pleading eyes.

“I’m Barry. I’m-” Barry stammered clutching the doorway tightly.

“You’re the Flash I know. That’s why I came to you to offer my help,” Alec said, “what’s wrong with you?”

“He was scratched by one of those demon creature things,” Cisco said. Barry couldn’t hold himself up any longer, his knees met the floor. Iris and Caitlin helped Barry back onto the bed.

“Show me the wound,” Alec said monotonously. He opened his backpack and took out a few small bottles in his hands. Caitlin turned Barry over onto his back, lifting up his shirt to expose the demon scratch.

“This remedy will help him recover, it’s an antidote for the scratch. Magnus, my warlock boyfriend, brewed it using magic that will help counteract the demon’s magic,” Alec took out some of the antidote which looked like a beige coloured cream. He placed some carefully onto the speedster’s back and felt Barry’s muscles relax instantly.

“That should help, just let him rest for a bit,” Alec said.

“Alright well now I’m convinced. So tell me Alec, how do we kill those demon things?” Cisco asked.

\----

When everyone was awake (with Barry almost fully recovered now with the help of the antidote), they sat around the main room of STARLabs listening to their newcomer as he explained everything.

“So these demons can only be killed by seraph blades like the ones you have or by magic?” Barry asked.

“Out of all the insane things we’ve faced including aliens, this is by far the craziest thing…” Cisco muttered with a sigh.

“And magic beats aliens?” Caitlin asked humoured.

“But if we have Magnus he can send these demons back to whichever demonic realm they came from,” Alec said.

“Your _magical_ boyfriend?” Cisco sneered.

 _“Cisco,”_ Barry scolded giving him the ‘are-you-really-going-to-do-this-now’ look and Cisco apologized.

“Well yes, Magnus is one of the most powerful warlocks in my world, but I would need to go back to ask for his help,” Alec said.

Just then an alarm went off startling everyone.

“Cisco?” Iris stood up striding over to the control panel. There was a video of a man with spiked hair and glittery black clothes burning down a building with demons at his side.

“Oh my god Magnus??” Alec gasped watching.

 _“That’s him?”_ Cisco stumped.

“Why are his eyes red? He has golden cat’s eyes this is so wrong what is he doing?” Alec asked pacing back and forth refusing to take his eyes off the screen.

“What does that mean?” Barry asked watching Alec.

“God damnit he’s been possessed. I didn’t think someone who’s born half demon can even be possessed!” Alec fired.

 _“Half demon?”_ Cisco hissed.

“Warlocks are half demon half human, while Shadowhunters are half angel half human,” Alec said matter-of-factly.

“This definitely beats aliens…” Cisco mumbled tapping on the screens.

“Let me talk to him. I can bring him back- I know it,” Alec turned to Team Flash.

“And if you can’t? You know we’ll have to take action. Possessed or not, he’s destroying our city and I can’t just stand and watch,” Barry said firmly.

“I can do it Barry,” Alec nodded so sure of himself. 

\-----

Barry, Cisco, and Alec arrived at the burning building, the sky above them was filled with fire and smoke. The heat was excruciating but Barry sped into the building to rescue the people inside and help put out the fire the way he usually did. Alec and Cisco found Magnus by the same time Barry caught up with them. Magnus turned around to face the three. He stared at Alec tilting his head.

“Magnus, hey, it’s me it’s Alec. You need to stop this now; the Magnus I know would never hurt innocent people. Please come back to me,” Alec pleaded desperately slowing taking small steps forward. 

“Kill them,” Magnus ordered and the five demons surrounding the warlock lunged forward. Alec had already given two of his seraph blades to Cisco and Barry who used them to defend themselves.

Alec fought his way to Magnus, “Magnus please!”

“Don’t make me do this Alexander!” Magnus yelled back his hands glowing red.

Alec stood directly in front of Magnus eyeing him, “I love you. I have ever since I saw you that day in Pandemonium. After everything we’ve been through, I won’t lose you. Please Magnus.” Magnus closed his eyes as if he was having trouble concentrating and then opened them. With his eyes flashing red, he pushed his hands forward throwing Alec against the wall of a nearby building. Barry quickly ran to check up on him. Alec opened his eyes slowly, trying to stand up.

“Alec it didn’t work,” Barry said apologetically. Alec stared at Magnus unable to believe he had lost his lover that easily.

“Barry behind you!” Cisco yelled from across the sidewalk. Before Barry could turn around, Alec pushed him out of the way. The demon stabbed Alec missing his heart by inches. Alec, by instinct, grabbed his remaining seraph blade and thrusted it into the demon causing it to combust and disintegrate. As the demon vanquished, Alec lost his balance and fell to the floor. Barry caught him just in time before Alec’s head met the ground. Cisco appeared at Barry’s side after destroying the final demon.

“We need to take him back to STARLabs,” Barry said looking up. He saw a dark figure walking towards him in the corner of his eyes, “Cisco…” But before Cisco could do anything, the dark figure, Magnus, used his magic to freeze Cisco into the floor.

“Barry I can’t move, get Alec out of here!” Cisco said panicking, his arms flailing about.

“Alexander?” Magnus murmured, his red eyes slowing turned back into gold. Magnus stared at Alec who was gasping in Barry’s arms. Barry gripped Alec tightly ready to run in a flash.

“Wait no stop it’s okay,” Magnus said rushing forward and kneeling beside Alec, “Alec can you hear me?” Magnus asked. When Alec didn’t say anything Magnus brought his hands out hovering them over Alec’s chest. He muttered something in a language Barry nor Cisco understood. After a short silence, Alec gasped opening his eyes. Magnus wrapped his hands around Alec hugging him placing a soft kiss on his cheek.

“You’re back,” Alec sighed with relief.

“This reunion is really lovely and all but oh great warlock can you please unfreeze my feet? I would really like them back,” Cisco coughed awkwardly. Magnus did so and stood up while lifting Alec to his feet.

“Alec tells us that you can get rid of these demons?” Barry asked stretching his arms.

“I can and I will but I’ll need a large open piece of land to create a portal,” Magnus inquired.

“I know just the place,” Barry nodded.

\-----

The four powered fighters arrived at the outskirts of Central City. Barry stood a little further away with Cisco watching Magnus mutter inaudibly. A massive dark hole appeared in front of Magnus and grew larger by the second.

“My God,” Cisco gasped watching the breath-taking event take place. Magnus yelled into the sky and stepped back to join Alec. The winged demons encircled above them before diving down into the Earth. This happened for a good few minutes before the hole in the ground closed up by itself.

“It is done.” Magnus rubbing his hands together.

“Thank you, we appreciate it,” Barry said nodding.

“How did so many breaches open simultaneously anyway?” Cisco asked intrigued.

“We’re not so sure but we’ll look into it and make sure it never happens again,” Alec confirmed.

“Well it’s been a pleasure doing business with you boys, but we must be on our way,” Magnus said.

“Of course, I’ll open a breach to your Earth,” Cisco stretched his hands out prepare himself.

“Thanks again- for everything. Take care of yourselves,” Barry smiled appreciatively hugging Magnus and Alec.

Cisco opened a breach carefully into the other Earth, “come visit us again sometime… except without the demons”. Magnus and Alec grinned hugging Cisco as a gesture of thanks and both stepped into the light blue cloud and disappeared.

“And here I though aliens were the craziest thing we’ve been a part of... boy, how wrong was I?"

**Author's Note:**

> It's pretty long but thought it would be an interesting and hilarious read! Hope you enjoyed it! :) xx


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